Low Dielectric Fluorinated Polynorbornene with Good Thermostability and Transparency Derived from a Biobased Allylphenol (Eugenol)

A new biobased functional norbornene was synthesized by the Diels–Alder reaction between cyclopentadiene and the fluorinated eugenol. Based on the norbornene monomer, a new polynorbornene was prepared with a high molecular weight (Mn = 78 000 Da) by the standard ring opening metathesis polymerization (ROMP). This polymer displayed good film-forming ability and can be postpolymerized to form a cross-linked network at high temperature (u003e150 °C) via the [2 + 2] cycloaddition reaction of trifluorovinyl ether (−OCF2═CF2) groups. The cross-linked polymer exhibited good transmittance (T % u003e 90% at 550 nm) and high thermostability with a 5% weight loss temperature of 412 °C. Moreover, no obvious glass transition temperature (Tg) was observed in the DMA measurement when the temperature was elevated near the decomposition temperature of the cross-linked polymer (about 350 °C). The cured resin displayed an average dielectric constant (Dk) of below 2.65 with average dissipation factor (Df) of 4.3 × 10–3 for the frequ...